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The conclusion section of Bailleul et al. (2020) Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage is:

The identification of chemical markers of DNA in Hypacrosaurus suggest it may preserve much longer than originally proposed [30,31]. Even though it is clear that contamination does exist in fossil material and complicates identifications of original organic molecules, it can be accounted for with proper controls. Contamination is not a plausible explanation in this case, and to this date, the possible preservation of original proteins and DNA in deep time has not been convincingly eliminated with data. Although extensive research and sequencing is required to further understand DNA preservation in Mesozoic material, along with its chemical and molecular alterations, our data suggest the preserved nuclear material in Hypacrosaurus was in a condensed state at the time of the death of the organism, which may have contributed to its stability. We propose that DNA condensation may be a favorable process to its fossilization. Additionally, as was suggested for protein fossilization [20,45,46], crosslinking may be another mechanism involved in the preservation of DNA in deep time.

The last three sentences highlight that "the preservation of DNA in deep time" may be aided by both DNA condensation and crosslinking.

Wikipedia's DNA condensation; in eukaryotes links to Chromatin

If I had to bet I'd say dinosaurs had chromatin but I could not defend it. If one of the conclusions of this paper was that the DNA was in a condensed state, then it sounds like they are not taking it for granted either.

Is this paper the full extent of what's known about DNA condensation in dinosaurs?

Together with condensation, crosslinking is mentioned in the conclusion, but a text search for "crossl" finds no other instances. As it seems closely related to condensation but there's no further information I don't see how to break that out as a separate question yet.

Question: How much is known about dinosaur DNA condensation and crosslinking?

Potentially related and/or helpful:

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  • 1
    $\begingroup$ I'd say about as much as is known in birds... $\endgroup$
    – bob1
    Mar 15 at 23:27
  • $\begingroup$ @bob1 actually known? $\endgroup$
    – uhoh
    Mar 15 at 23:37
  • 4
    $\begingroup$ Well, no, not actually known, given that there's 65 My between then and now, but I doubt such important mechanisms have changed much in the intervening time. $\endgroup$
    – bob1
    Mar 15 at 23:54
  • $\begingroup$ @LifeInTheTrees It can not fail if it does not try. It does not try because as far as I can understand (not being a molecular biologists) they simply did not search for DNA. This is in fact what makes the paper so intriguing and tantalizing! However, my question is not about this paper specifically (it's provided as evidence of prior research and what got me interested in this. There is likely more known on the topic (I have linked to a second paper just as an example) but probably not much more, and so I've simply asked "How much is known...?" $\endgroup$
    – uhoh
    Mar 16 at 12:10
  • $\begingroup$ Of course dinosaurs had chromatin. Histones — a key constituent of chromatin — are present in eukaryotes as primitive as yeast. I am not aware of any way to establish the condensation state of fossil chromatin, nor would I imagine it to attract much interest, but I may be wrong. $\endgroup$
    – David
    Apr 3 at 20:06

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